This invention relates to hand-held tufting machines and more particularly to a hand-held tufting machine using pneumatic power wherein an operator can precisely control the operation of the stitch forming instrumentalities.
Hand-held tufting machines, also known as mending guns, are universally used for correcting faults in tufted fabric such as carpeting. For example, if for some reason, such as a broken yarn, one or a few needles of a tufting machine in the manufacture of carpeting do not form stitching in the backing material, the missing stitches are inserted by the use of such mending guns. Known prior art mending guns are illustrated in U.S. Pat. Nos. 2,753,820; 2,837,045; 2,862,466; 2,879,731; 2,887,076; 3,142,276; 3,144,844; 3,225,723; 3,229,653; 3,389,667; 3,645,219; 4,006,694; 4,007,698; 4,132,182; and 4,388,881. Other uses of such guns may be found in the manufacture of customized rugs.
Because of the ready availability of the supply of compressed air in carpet mills most of the current mending guns are pneumatically driven, the gun having a small pneumatic rotary turbine motor within the handle for reciprocably driving the needle. Other such guns which use an electric motor for driving the needle are generally used for manufacturing customized rugs or for craft purposes where a supply of pressurized air is not readily available. The only known proposal for a pneumaticaly driven mending gun not having a rotary motor is that illustrated in the aforesaid U.S. Pat. No. 4,388,881 assigned to the common assignee of the present invention. There a piston/cylinder assembly was proposed with the piston reciprocating within a pivotably mounted housing that cyclically pivoted in alternate directions with each stroke of the piston to open and close ports in the piston housing for ingress and egress of air. The piston was double acting and as it reached the end of its stroke at each end of the piston housing, the housing pivoted to receive high pressure air at the end reached by the piston so as to drive the piston in the reverse direction. The piston was eccentrically mounted to a crank for driving the needle. Because of the complexities of the pivotable housing arrangement, that proposal was never adopted for manufacture. It may be pointed out that in all of the aforesaid patents the mending guns or hand-held tufters utilized some form of crank driven stitch forming instrumentalities.
The mending guns currently utilized in carpet mills are of the type illustrated in the aforesaid U.S. Pat. Nos. 3,225,723 and 3,645,219. These mending guns since they are driven by pneumatic motors drive the needle and other stitch forming instrumentalities in a very rapid manner. Although this is desirable for unpatterned carpet fabric since all the operator has to do is hold the presser foot of the gun against the backing material along the row in which the tufting machine did not form stitching and feed the gun to fill in the missing stitches. The rapid action of the stitch forming instrumentalities is therefore useful in such instances. However, a substantial amount of patterned carpet fabric is currently being manufactured, such patterning being performed by sliding one or more needle bars of the tufting machine laterally so that an array of various zig-zag stitches are formed on the backing material surface remote from the pile surface. Some of the patterns are such that some zig-zag stitches overlay other zig-zag stitches. Because of the rapid action of the known mending guns, the operator has no control as to the placement of the stitches applied by the mending gun. Once the trigger of the gun is squeezed, a substantial number of stitches are formed, and it becomes difficult, if not virtually impossible, for an operator to place an array of zig-zag stitching into the backing material where a tufting machine needle has omitted the zig-zag stitch. When this occurs, defective fabric is produced thereby increasing the manufacturing costs.